Update readme.python.md (#15741)

Author: BigCat20196

specification/compute/resource-manager/readme.python.md

@@ -36,6 +36,7 @@ Generate all API versions currently shipped for this package
 ```yaml $(multiapi)
 clear-output-folder: true
 batch:
+  - tag: package-2021-07-01-only
   - tag: package-2021-04-01-only
   - tag: package-2021-03-01-only
   - tag: package-2020-12-01-only
@@ -68,6 +69,17 @@ clear-output-folder: false
 perform-load: false
 ```
 
+### Tag: package-2021-07-01-only
+
+These settings apply only when `--tag=package-2021-07-01-only --python` is specified on the command line.
+Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
+
+``` yaml $(tag) == 'package-2021-07-01-only'
+namespace: azure.mgmt.compute.v2021_07_01
+output-folder: $(python-sdks-folder)/compute/azure-mgmt-compute/azure/mgmt/compute/v2021_07_01
+```
+
+
 ### Tag: package-2021-04-01-only
 
 These settings apply only when `--tag=package-2021-04-01-only --python` is specified on the command line.